In the proposed work, the role of papovavirus infections in the etiology of human bladder cancer will be evaluated. Cells grown from bladder tumors will be examined for the presence of virus-specific antigens of papovaviruses SV40, BK and JC. Serologic studies will be performed to determine if the prevalence of antibodies to structural T antigens of these viruses is higher in bladder cancer cases as compared to that in control groups.